| 摘要 |
<p>PURPOSE:To make a memory or a backup battery required in a conventional device unnecessary, by providing a bus which connects a main microcomputer to a sub microcomputer, and a power source control circuit which can turn on and off the power source of the sub microcomputer from the main microcomputer. CONSTITUTION:When the power source is turned on, and a power source switch 15 is switched to a side to turn off the power source, the main microcomputer 11 recognizes it, and transfers a bit of information representing the diconnection of the power source to the sub microcomputer 12. The sub microcomputer 12 receiving the information performs the data transfer of a data desired to be preserved for backup to the main microcomputer 11. The main microcomputer 11, after receiving the data, turns off the power source Vcc of the sub microcomputer 12 by operating the power source control circuit 14. Next, at the time of switching the power source switch 15 to an ON side, the main microcomputer 11 recognizes it, and turns on the power source of the sub microcomputer 12 through the power source control circuit 14. Afterwards, the data transferred just before turning off the power source of the sub microcomputer 12 is returned to the sub microcomputer 12.</p> |
